There are a couple types of pumps for wells, especially deep wells such as oil wells. The most commonly used pumps include pump jacks or reciprocating pumps. Pump jacks or reciprocating pumps use small diameter pumps that fit down in a well and are fitted to discharge tubing that is used to transport fluid to the surface. These pumps are often operated by sucker rods, which operate the pump pneumatically. Examples of these types of pumps are disclosed in U.S. Pat. Nos. 1,603,675 and 2,180,864. Problems often occur with these types of pumps because of the weight of the fluid and the power required to pump it up the long column (which can be thousands of feet long) formed by thirty-foot sections of discharge tube. When these problems occur, the discharge tubing and sucker rods must be disassembled before the pump can be brought to the surface for repair.
Another type of pump that is currently being used is a bailer pump. These pumps operate much like the ancient rope and bucket approach. A bailer is lowered into the well and allowed to sit in the fluid long enough for it to fill the bailer. A timer is often used to control the amount of time the bailer is in the fluid to insure that fluid has had enough time to seep into the bailer to fill it before the bailer is pulled to the surface and emptied. An example of this type of well is shown and described in U.S. Pat. No. 4,086,035. Often the issue with these types of pumps is that they are not very efficient. Time is lost because the bailer is sent to a constant depth which is often well below the surface level of the fluid to insure that it recovers fluid with each cycle. Fluid typically enters a hole in the bottom of the bailer and a check valve is used to prevent it from leaking out when the bailer is brought to the surface. Further, for oil wells, if water is present and rises to that predetermined level, water will be recovered with the oil. Time may also be lost waiting for the fluid to seep into the bailer, if the seepage rate is unknown. Plus a mess is likely when the bailers are dumped at the surface.